BIOL 211 Lecture Notes - Lecture 1: Issf 10 Meter Air Rifle, Radiometric Dating
31 Aug 2016
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Document Summary
Idea that layers of rock are younger than the ones below the surface. Relative dates - younger or older, shows the order. Typically carried out in igneous or metamorphic rocks. Measures time since molten rock cooled sufficiently to prevent loss of daughter isotope . Ex: k-40 (liquid) ar-40 (gas, daughter isotope) When rock solidifies, there is 100% kr-40 0% ar-40. Kr-40 has half life of 1. 3 billion years. Only usable to 50,00 years before present. Fact- something that can be observed to occur. Hypothesis- a prediction on what will happen in a certain set of circumstances. Law- a universal relationship describing how the natural world behaves under specific conditions. Theory- an explanation consistent with all known facts and all applicable natural laws. 4,500 million years ago was the formation of earth. 3,800- 3,500 mya = origin of life. 2,200 mya atmospheric oxygen concentration begins to increase. 470 mya = oldest fossils of land plants.
